Population genetic structure and conservation genetics of threatened Okaloosa darters (Etheostoma okaloosae)
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Imperiled Okaloosa darters (Etheostoma okaloosae) are small, benthic fish limited to six streams that flow into three bayous of Choctawhatchee Bay in northwest Florida, USA. We analyzed the complete mitochondrial cytochrome b gene and 10 nuclear microsatellite loci for 255 and 273 Okaloosa darters, respectively. Bayesian clustering analyses and AMOVA reflect congruent population genetic structure in both mitochondrial and microsatellite DNA. This structure reveals historical isolation of Okaloosa darter streams nested within bayous. Most of the six streams appear to have exchanged migrants though they remain genetically distinct. The U.S. Fish and Wildlife Service recently reclassified Okaloosa darters from endangered to threatened status. Our genetic data support the reclassification of Okaloosa darter Evolutionary Significant Units (ESUs) in the larger Tom’s, Turkey, and Rocky creeks from endangered to threatened status. However, the three smaller drainages (Mill, Swift, and Turkey Bolton creeks) remain at risk due to their small population sizes and anthropogenic pressures on remaining habitat. Natural resource managers now have the evolutionary information to guide recovery actions within and among drainages throughout the range of the Okaloosa darter.
KeywordsAMOVA Bayesian cluster analysis Distinct population segments Endangered Evolutionary significant units Phylogeography
We thank B. Garner for her assistance with genotyping. L. Jelks greatly improved the readability of this manuscript. Funding for this research was provided by the Florida Fish and Wildlife Conservation Commission Nongame Grant Program and the U.S. Department of Defense. The findings and conclusions in this article are those of the authors and do not necessarily represent the views of the U.S. Fish and Wildlife Service. Mention of trade names or commercial products does not imply endorsement by the U.S. Government.
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